Reactions of Polynuclear Hydroxyaluminum Cations with Montmorillonite and the Formation of A 28-Å Pillared Complex1

S. Shah Singh and H. Kodama
Land Resource Research Centre, Research Branch, Agriculture Canada Ottawa, Ontario K1A 0C6, Canada
1 Land Resource Research Centre Contribution 87-89.

Abstract: Polynuclear hydroxy-Al cations were prepared by partially neutralizing dilute solutions of aluminum chloride. These cations were introduced in the interlayer space of montmorillonite by cation exchange, which formed heat-stable pillars between the silicate layers. Polynuclear hydroxy-Al was preferentially adsorbed on montmorillonite compared with monomer-Al; the maximum amount adsorbed was ∼400 meq/100 g of montmorillonite. Of this amount 320 meq was non-exchangeable. The 001 X-ray powder diffraction reflection of the polynuclear hydroxy-Al-montmorillonite complex was at 27 Å, with four additional higher-order basal reflections, giving an average d(001) value of 28.4 Å. This complex was thermally stable to 700°C. An analysis of the basal reflections by the Fourier transform method indicated that the 28-Å complex had a relatively regular interstratified structure of 9.6- and 18.9-Å component layers with a mixing ratio of 0.46:0.54. This ratio implies that the hydroxy-Al pillars occupied every second layer. Considering the relatively small amount of Al adsorbed and the thermally stable nature of the structure, the hydroxy-Al pillars must have been sparsely but homogeneously distributed in the interlayer space.

Key Words: Fourier transform • Hydroxy-Al • Montmorillonite • Pillared interlayer complex • Thermal stability

Clays and Clay Minerals; October 1988 v. 36; no. 5; p. 397-402; DOI: 10.1346/CCMN.1988.0360503
© 1988, The Clay Minerals Society
Clay Minerals Society (www.clays.org)